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Offline Issues

Cashier Manager Admin

Brother POS is designed to keep selling even when your internet connection drops. The POS register queues cash transactions locally in the browser and syncs them to the server when connectivity is restored. This page covers problems that can occur with the offline queue and how to resolve them.

How Offline Mode Works​

Understanding the offline system helps with troubleshooting:

  1. Connection monitoring. The POS continuously monitors server connectivity. When the connection is lost, the POS switches to offline mode and displays a visual indicator in the header.

  2. Local caching. Products and store settings are cached locally so the POS remains functional. You can browse products, search the catalog, and build carts.

  3. Offline queue. When a sale is completed while offline, the transaction data is saved to the browser's local database regardless of payment method. This is a persistent database that survives page refreshes and browser restarts.

  4. Automatic sync. When the connection is restored, the POS automatically processes the queued transactions in order, sending each one to the server.

  5. Status indicator. The POS header shows the current status:

    • Online -- normal operation, all features available
    • Offline -- no server connection, sales queued locally
    • Syncing -- connection restored, processing queued transactions
Offline limitations

While offline, the POS cannot:

  • Communicate with integrated payment terminals (actual card processing depends on the terminal's offline capability)
  • Verify real-time inventory levels
  • Apply sale campaigns that require server validation

Customer and loyalty data may be stale when offline -- changes made on other devices will not be reflected until sync. All payment types can be recorded and queued offline, though integrated terminal transactions may not process until connectivity returns.

Sales Stuck in Offline Queue​

Problem​

The network has been restored but queued offline sales are not syncing to the server. The POS may show a count of pending transactions or the "Syncing" status indicator may not appear.

Solutions​

  1. Verify the connection is actually restored. Just because WiFi is connected does not mean the server is reachable.

    • Open a new browser tab and navigate to your store URL (storename.brotherpos.ca). If it loads, the server is reachable.
    • Check the POS header indicator. It should show "Online" or "Syncing."

  2. Refresh the POS page. A page refresh triggers the sync process.

    • Regular refresh: F5 or Ctrl+R
    • Hard refresh: Ctrl+Shift+R (bypasses service worker cache)

  3. Wait for the sync to complete. If you have many queued transactions (10+), the sync process can take a minute or two. Each transaction is processed sequentially to maintain order integrity.

  4. Check for sync errors. If individual transactions fail to sync, the POS may show an error indicator next to the failed transaction in the offline queue. Common reasons for sync failure:

    • A product in the sale no longer exists on the server (it was deleted while offline).
    • The cash drawer session has been closed by another user.
    • The server rejected the transaction due to validation errors.

  5. Do not clear browser data. If you have unsent offline sales, clearing browser data will permanently delete those transactions.

Do not clear browser data

If the offline queue contains pending sales, do not clear your browser cache, cookies, or site data. Doing so will permanently delete the queued transactions, and the revenue from those sales will be lost. Always ensure the queue is empty before clearing browser data.

Sync Failures When Back Online​

Problem​

Some or all queued transactions fail to sync when the connection is restored. You may see error messages or a persistent count of unsent transactions.

Solutions​

  1. Check the error details. If the POS provides specific error messages for failed transactions, those messages will guide you:

    • "Product not found" -- A product was deleted from the catalog while the POS was offline. The sale data is preserved but cannot be automatically synced. Contact your manager.
    • "Session closed" -- The cash drawer session was closed while you were offline. A manager needs to either reopen a session or handle the orphaned transactions.
    • "Validation error" -- The sale data does not meet current server requirements (for example, a required customer field was added while offline).

  2. Ask your manager to review. Managers can view the offline queue status and decide how to handle failed transactions. Options include:

    • Retrying the sync after fixing the underlying issue (such as recreating a deleted product).
    • Manually recording the transactions in the admin panel.
    • Discarding the failed transactions if they were test sales or duplicates.

  3. Check for duplicate sales. If a sync attempt was partially successful (the server received the data but the POS did not get the confirmation), the same sale might be sent again on retry. Check recent sales in the admin panel for duplicates.

  4. Retry the sync manually. Refresh the page to trigger another sync attempt. If the underlying issue has been resolved (such as reopening the cash drawer session), the previously failed transactions should sync successfully.

Offline Queue Not Working​

Problem​

Completing a sale while offline does not queue the transaction. The sale appears to vanish.

Solutions​

  1. Check local storage availability. Some browser settings, privacy modes, or security software can disable browser local storage.

    • Open developer tools (F12) > Application > Storage.
    • If no databases are listed, local storage may be disabled or blocked.
    • Try disabling incognito/private mode -- some browsers restrict local storage in private browsing.

  2. Check available storage. If the device's storage is full, the browser cannot write to the local database.

    • Free up space on the device.
    • Check if the browser's storage quota has been exceeded.

  3. Check for browser restrictions. Some enterprise-managed browsers have policies that restrict local storage. Contact your IT administrator if the POS is running on a managed device.

  4. Use a supported browser. The offline queue is supported in all modern browsers, but older versions may have bugs. Use Chrome 90+ or Edge 90+ for best results.

Stale Product Data While Offline​

Problem​

Products displayed in the POS while offline do not reflect recent changes made in the admin panel (such as price updates, new products, or deactivated products).

Explanation​

The product catalog is cached locally for offline use. This cache is updated whenever the POS loads while online. If the POS was last loaded before changes were made, the cached data will be stale.

Solutions​

  1. This is expected behavior. While offline, the POS cannot fetch the latest product data from the server. Sales processed offline will use the cached prices.

  2. Refresh when back online. Once the connection is restored, refresh the POS page. The product cache will be updated with the latest data from the server.

  3. Review offline sales for pricing accuracy. If significant price changes were made while a register was offline, review the offline sales after they sync to ensure the prices were acceptable.

Pricing during offline sales

Offline sales use the prices that were in effect when the POS was last online. If a price changed on the server while the register was offline, the old price will be used for the offline sale. The server records the sale at whatever price the POS sent during sync.

Preventing Offline Issues​

  1. Use a wired connection. Ethernet connections are far more stable than WiFi. For stationary registers, always prefer wired connections.

  2. Keep the POS page open. Do not close the POS browser tab at the end of the day if you want to maintain the product cache. The cached data persists as long as the browser data is not cleared.

  3. Refresh the POS daily. Refresh the POS page at the start of each day (while online) to ensure the product cache has the latest data.

  4. Monitor your network. If you experience frequent offline episodes, consider upgrading your internet service or adding a backup connection. See Network Issues.

  5. Process card payments first when unstable. If your connection is intermittent, process card payments (which require a live connection) before the connection drops. Cash sales can be queued offline, but card sales cannot.

Checking Offline Queue Status​

To see if there are pending offline transactions:

  1. Check the sync status indicator in the header bar. It shows the current connection state and any pending transaction count.
  2. If there are pending transactions, the POS will show how many are waiting to sync.

You can also check in developer tools:

  1. Open developer tools (F12).
  2. Go to Application > Storage.
  3. Look for Brother POS database entries. Pending transactions will be stored in the offline queue.

Data Integrity​

Brother POS ensures offline data integrity through several mechanisms:

MechanismPurpose
Sequential processingQueued transactions sync in order to maintain chronological integrity
Conflict detectionThe server checks for conflicts (like negative inventory) during sync
Transaction IDsEach offline transaction gets a unique local ID to prevent duplicates
Retry logicFailed sync attempts are retried automatically without duplicating data

When to Contact Support​

Contact your admin or Brother POS support if:

  • Offline transactions consistently fail to sync despite a stable connection
  • The offline queue shows transactions that cannot be retried or dismissed
  • You suspect data loss from cleared browser storage with pending transactions
  • The POS does not switch to offline mode when the connection drops